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The inward bulge type buckling of monocoque cylinders 3: revised theory which considers the shear strain energy

Description: Report presenting the third part of an investigation dealing with the inward bulge type buckling of monocoque cylinders the theory of buckling in pure bending, which is refined through the consideration of the shear strain energy stored in the sheet covering, the assumption of a revised deflected shape of the rings, and the use of summations in place of some of the integrations of the preceding report.
Date: April 1945
Creator: Hoff, N. J. & Klein, Bertram
Partner: UNT Libraries Government Documents Department

Bilinear Cyclic Stress-Strain Parameters for Types 304 and 316 Stainless Steel

Description: The bilinear cyclic stress-strain parameters for Types 304 and 316 stainless steel are described. The bilinear properties of solution-annealed and aged Type 304 stainless steel (heat 9T2796) and solution-annealed Type 3l6 stainless steel (heat 8092297) under cyclic-loading conditions at a strain rate of 8.6 x 10⁵ s⁻¹, total strain range between 0.2 and 0.8 percent, and temperatures from 22 to 593 degrees C were determined. The dependence of bilinear parameters on maximum strain epsilon and temperature is discussed.
Date: July 1978
Creator: Maiya, P. S.
Partner: UNT Libraries Government Documents Department

Analysis of Stresses in Bellows

Description: Abstract: Design charts and systematic design forms are presented for simplified calculations to check the number of convolutions and thickness required to limit the deflection and pressure stress range in three types of bellows.
Date: October 15, 1964
Creator: Anderson, W. F.
Partner: UNT Libraries Government Documents Department

Device for Measuring Principal Curvature and Principal Strains on a Nearly Plane Surface

Description: Note presenting a device which makes possible the measurement of principal extreme fiber bending strains over a circular area with a radius of 0.94 inch with a systematic error on 0.1-inch sheet of the order of 0.00003. Equations are presented for computing median fiber strains from the measured curvatures and strains at the surface and from the thickness of the sheet.
Date: February 1947
Creator: McPherson, A. E.
Partner: UNT Libraries Government Documents Department

Performance Tests of Wire Strain Gages 5: Error in Indicated Bending Strains in Thin Sheet Metal Due to Thickness and Rigidity of Gage

Description: Note presenting the results of tests to determine the combined effects of rigidity and thickness of wire strain gages on indicated bending strains in thin sheet metal for 15 types of single-element multistrand wire strain gages. In most cases, the indicated extreme-fiber bending strain was greater than the actual strain. The positive error caused by the finite thickness of the gage predominated over the negative error caused by the rigidity of the gage.
Date: July 1947
Creator: Campbell, W. R. & Medbery, A. F.
Partner: UNT Libraries Government Documents Department

Monte-Carlo simulation of surface growth. Final report for period September 15, 1997-September 14, 2001

Description: We have carried out simulations using various methods on models of epitaxial growth. We have investigated both homoepitaxial as well as heteroepitaxial growth. We have studied the effects of evaporation, island coarsening, strain due to lattice mismatch, three dimensional islands submonolayer growth, and self-organization in quantum dot superlattices. The results of our investigations are of significance to the understanding of material properties at the nanoscale.
Date: December 1, 2000
Creator: Lam, Pui-Man
Partner: UNT Libraries Government Documents Department

Extensions of the Stoney Formula for Substrate Curvature to Configurations with Thin Substrates or Large Deformations

Description: Two main assumptions which underlie the Stoney formula relating substrate curvature to mis-match strain in a bonded thin film are that the film is very thin compared to the substrate, and the deformations are infinitesimally small. Expressions for the curvature-strain relastionship are derived for cases in which thses assumptions are relaxed, thereby providing a biasis for interpretation of experimental observations for a broader class of film-substrate configurations.
Date: April 26, 1999
Creator: Chason, E.; Floro, J.A. & Freund, L.B.
Partner: UNT Libraries Government Documents Department

Self-Organized Vertical Superlattices in Epitaxial GaInAsSb

Description: Self-organized superlattices are observed in GaInAsSb epilayers grown nominally lattice matched to vicinal GaSb substrates. The natural superlattice (NSL) is detected at the onset of growth; is continuous over the lateral extent of over several microns; and persists vertically throughout several microns of the epilayer. Furthermore, the NSL is inclined by an additional 4{sup o} with respect to the vicinal (001) GaSb substrate. The tilted NSL intersects the surface of the epilayer, and the NSL period is geometrically correlated with surface undulations. While the principle driving force for this type of phase separation arises from solution thermodyamics, the mechanism for the self-organized microstructure is related to local strains associated with surface undulations. By using a substrate with surface undulations, the tilted NSL can be induced in layers with alloy compositions that normally do not exhibit this self-organized microstructure under typical growth conditions. These results underscore the complex interactions between compositional modulations and morphological perturbations.
Date: February 9, 2004
Creator: Wand, CA; Vineis, CJ & Calawa, DR
Partner: UNT Libraries Government Documents Department

An Experimental Investigation of a Prescription for Identifying Plastic Strain

Description: A series of experiments is described in which a novel prescription for the identification of plastic strain is tested to determine its validity in the context of the strain-space formulation of rate-independent plasticity. Biaxial experiments were performed on several thin-walled aluminum 1100-O cylindrical specimens.
Date: February 29, 2000
Creator: Brown, A.A.; Casey, J. & Nikkel, D.J.
Partner: UNT Libraries Government Documents Department

Effects of Airplane Flexibility on Wing Strains in Rough Air at 5,000 Feet as Determined by Flight Tests of a Large Swept-Wing Airplane

Description: Report presenting a flight investigation of a large swept-wing bomber airplane in rough air at 5,000 feet to determine the effects of wing flexibility on wing bending and shear strains. Aeroelastic effects were found to be large, particularly at the outboard measuring stations. Results regarding the bending strains and shear strains are provided.
Date: September 1957
Creator: Rhyne, Richard H. & Murrow, Harold N.
Partner: UNT Libraries Government Documents Department

Effects of Airplane Flexibility on Wing Strains in Rough Air at 35,000 Feet as Determined by a Flight Investigation of a Large Swept-Wing Airplane

Description: A flight investigation was made on a large sweptback-wing bomber airplane and the results are compared with data previously obtained at low altitude (5,000 feet). The effects of wing flexibility on the wing strains were, on the average, about 20 percent larger at the higher altitude.
Date: January 1958
Creator: Rhyne, Richard H.
Partner: UNT Libraries Government Documents Department

Finite-Element Analysis of a Thick-Wall Tube Containing a Crater-Like Surface Flaw

Description: A three-dimensional finite-element elastic analysis is carried out for a thick-wall tube (as sued in typical LMFBR steam generators) that contains a surface flaw in the form of a paraboloid of revolution. Effects of the depth and aspect ratio of the flaw on the stress distribution and stress concentration in the tube are explored.
Date: June 1976
Creator: Majumdar, S.
Partner: UNT Libraries Government Documents Department

Draft genome sequence of Therminicola potens strain JR

Description: 'Thermincola potens' strain JR is one of the first Gram-positive dissimilatory metal-reducing bacteria (DMRB) for which there is a complete genome sequence. Consistent with the physiology of this organism, preliminary annotation revealed an abundance of multiheme c-type cytochromes that are putatively associated with the periplasm and cell surface in a Gram-positive bacterium. Here we report the complete genome sequence of strain JR.
Date: July 1, 2010
Creator: Byrne-Bailey, K.G.; Wrighton, K.C.; Melnyk, R.A.; Agbo, P.; Hazen, T.C. & Coates, J.D.
Partner: UNT Libraries Government Documents Department

Probing the evolution of antiferromagnetism in multiferroics

Description: This study delineates the evolution of magnetic order in epitaxial films of the room-temperature multiferroic BiFeO3 system. Using angle- and temperature-dependent dichroic measurements and spectromicroscopy, we have observed that the antiferromagnetic order in the model multiferroic BiFeO3 evolves systematically as a function of thickness and strain. Lattice-mismatch-induced strain is found to break the easy-plane magnetic symmetry of the bulk and leads to an easy axis of magnetization which can be controlled through strain. Understanding the evolution of magnetic structure and how to manipulate the magnetism in this model multiferroic has significant implications for utilization of such magnetoelectric materials in future applications.
Date: June 9, 2010
Creator: Holcomb, M.; Martin, L.; Scholl, A.; He, Q.; Yu, P.; Yang, C.-H. et al.
Partner: UNT Libraries Government Documents Department

Goddard rattler-jamming mechanism for quantifying pressure dependence of elastic moduli of grain packs

Description: An analysis is presented to show how it is possible for unconsolidated granular packings to obey overall non-Hertzian pressure dependence due to the imperfect and random spatial arrangements of the grains in these packs. With imperfect arrangement, some gaps that remain between grains can be closed by strains applied to the grain packing. As these gaps are closed, former rattler grains become jammed and new stress-bearing contacts are created that increase the elastic stiffness of the packing. By allowing for such a mechanism, detailed analytical expressions are obtained for increases in bulk modulus of a random packing of grains with increasing stress and strain. Only isotropic stress and strain are considered in this analysis. The model is shown to give a favorable fit to laboratory data on variations in bulk modulus due to variations in applied pressure for bead packs.
Date: January 5, 2009
Creator: Pride, Steven R. & Berryman, James G.
Partner: UNT Libraries Government Documents Department

Formation mechanism and properties of CdS-Ag2S nanorod superlattices

Description: The mechanism of formation of recently fabricated CdS-Ag{sub 2}S nanorod superlattices is considered and their elastic properties are predicted theoretically based on experimental structural data. We consider different possible mechanisms for the spontaneous ordering observed in these 1D nanostructures, such as diffusion-limited growth and ordering due to epitaxial strain. A simplified model suggests that diffusion-limited growth partially contributes to the observed ordering, but cannot account for the full extent of the ordering alone. The elastic properties of bulk Ag{sub 2}S are predicted using a first principles method and are fed into a classical valence force field (VFF) model of the nanostructure. The VFF results show significant repulsion between Ag{sub 2}S segments, strongly suggesting that the interplay between the chemical interface energy and strain due to the lattice mismatch between the two materials drives the spontaneous pattern formation.
Date: August 11, 2008
Creator: Wang, Lin-Wang; Demchenko, Denis O.; Robinson, Richard D.; Sadtler, Bryce; Erdonmez, Can K.; Alivisatos, A. Paul et al.
Partner: UNT Libraries Government Documents Department